Interactions between contaminants and the trophic ecology of two seabirds in a coastal lagoon of the Gulf of California.

Monitoring the dynamics of contaminants in ecosystems helps understand their potential effects. Seabirds have been used as biomonitors of marine ecosystems for this purpose. However, exposure and vulnerability to pollutants are understudied in tropical species, and the relationships between various pollutants and the trophic ecology of seabirds are poorly understood.

Seasonal and between-population variation in heat tolerance and cooling efficiency in a Mediterranean songbird.

Discrete populations of widely distributed species may inhabit areas with marked differences in climatic conditions across geographic and seasonal scales, which could result in intraspecific variation in thermal physiology reflecting genetic adaptation, phenotypic plasticity, or both. However, few studies have evaluated inter-population variation in physiological responses to heat. We evaluated within- and inter-population seasonal variation in heat tolerance, cooling efficiency and other key thermoregulatory traits in two Mediterranean populations of Great tit Parus major experiencing contrasting thermal environments: a lowland population subject to hotter summers and a higher annual thermal amplitude than a montane population.

Egg size variation in the context of polyandry: a case study using long-term field data from snowy plovers.

Gamete size variation between the sexes is central to the concept of sex roles, however, to what extent gamete size variation within the sexes relates to sex role variation remains unclear. Comparative and theoretical studies suggest that, when clutch size is invariable, polyandry is linked to a reduction of egg size, while increased female-female competition for mates favors early breeding when females cannot monopolize multiple males. To understand whether and how breeding phenology, egg size, and mating behavior are related at the individual level, we studied the reproductive histories of 424 snowy plover females observed in the wild over a 15-year period.

Mediterranean songbirds show pronounced seasonal variation in thermoregulatory traits.

Addressing the patterns of variation in thermal traits is crucial to better predict the potential effects of climate change on organisms. Here, we assessed seasonal (winter vs summer) adjustments in key thermoregulatory traits in eight Mediterranean-resident songbirds. Overall, songbirds increased whole-animal (by 8%) and mass-adjusted (by 9%) basal metabolic rate and decreased (by 56%) thermal conductance below the thermoneutral zone during winter.

Heat tolerance limits of Mediterranean songbirds and their current and future vulnerabilities to temperature extremes.

Songbirds are one of the groups most vulnerable to extreme heat events. Although several recent studies have assessed their physiological responses to heat, most of them have focused solely on arid-zone species. We investigated thermoregulatory responses to heat in eight small-sized songbirds occurring in the Mediterranean Basin, where heatwaves are becoming more frequent and intense.

The thermoregulatory role of relative bill and leg surface areas in a Mediterranean population of Great tit ().

There is growing evidence on the role of legs and bill as 'thermal windows' in birds coping with heat stress. However, there is a lack of empirical work examining the relationship between the relative bill and/or leg surface areas and key thermoregulatory traits such as the limits of the thermoneutral zone (TNZ) or the cooling efficiency at high temperatures. Here, we explored this relationship in a Mediterranean population of Great tit () facing increasing thermal stress in its environment.

Going to sleep with a full belly: Thermal substitution by specific dynamic action in shorebirds.

Many bird species occupy habitats where environmental temperatures fall well below their thermoneutral zone (TNZ), so they must deal with high energy costs of thermoregulation to keep in heat balance. In such circumstances, specific dynamic action (SDA) - also referred to as heat increment of feeding - could be used to substitute for these high thermoregulatory costs. If birds ingest food before going to roost in cold environments, the SDA will be beneficial as an energy-conserving mechanism by thermal substitution.

Mate selection based on labile traits affects short-term fitness in a long-lived seabird.

In long-lived monogamous social species, partner compatibility can play a crucial role in reproductive success. We evaluated assortative mating based on body condition (plasma triglyceride concentration), diet (δN), and foraging habitat (δC) in the blue-footed booby , a long-lived monogamous seabird. We investigated the effects of assortative mating (sum of triglycerides in a pair) and asymmetry within pairs (residuals from regression of female-male triglycerides) on reproductive performance and offspring growth (alkaline phosphatase, ALP).

Correction: High quality diet improves lipid metabolic profile and breeding performance in the blue-footed booby, a long-lived seabird.

[This corrects the article DOI: 10.1371/journal.pone.

High quality diet improves lipid metabolic profile and breeding performance in the blue-footed booby, a long-lived seabird.

Understanding the role of diet in the physiological condition of adults during reproduction and hence its effect on reproductive performance is fundamental to understand reproductive strategies in long-lived animals. In birds, little is known about the influence of the quality of food consumed at the beginning of the reproductive period and its short-term effects on reproductive performance. To assess the role of diet in the physiological condition of female blue-footed booby, Sula nebouxii (BFBO), during reproduction we evaluated whether individual differences in diet (assessed by using δ13C and δ15N values of whole blood from female birds and muscle tissue of the principal prey species) prior to egg laying and during incubation influenced their lipid metabolic profile (measured as triglyceride levels and C:N ratio) and their reproductive performance (defined by laying date, clutch size and hatching success).